Core and method of making same.



M0. 65u05. Patented lune l2, leon.

M. H. FLETCHER. comi AND METHuu 0F MAKING SAME.

(Application led Jan. 13, 1896.)

(No Model.)

`mz Norms PETERS co.. PNuTuuruQmAsHmaroN, n. c.

"Unirse STATES PATENT OFFICE;

MORDCAI H. FLETCHER, OF CINCINNATI, OHIO.

CORE AND METHOD OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 651,705, dated June 12, 1900. Application filed (l'anuary 13, 1896. `Serial No. 575,265. (No model.)

T @ZZ 'tu/"tom, t may concern:

Be it known that LMORDEOAI H. FLETCHER, a citizen of the United States,residing at Cincinnati, Ohio, have invented new and useful Improvements in Cores and the Method of Making the Same, of which the following is a specification.

My invention relates to methods of manu-` faeturing cores employed in casting hollow articles-such, for example, as hollow cylindersmwherein a core-surface of sand and loam is superimposed upon a core-bar of metal. In forming such cores for casting pipe, &c., for water and gas mains and similar cylindrical objects the ordinary practice is to first enwrap the core-bar with a rope of hay in adjacent convolutions and upon this place a coating of plastic clay, upon which, when dried, is placed a final concentric layer of loam, forming the surface of the core for casting. There is thus produced a combustible foundation layer for the clay and loam, which is burned away by the heat of the molten metal, thus leaving space between the clay layer and the core-bar, facilitating the escape of the gases engendered in casting and enabling the core-bar to be withdrawn. The earthy layers being thus left without support may be broken from the interior of the cast;I ing. Besides the expense of manipulation and the cost of material dcstroyed,this method of procedure is subject to further objection in this, namely, that the layer formed by the hay rope is unequally compressible and produces irregularity in the contour and dimensions of the casting under the compression of the molten metal,often seriouslyimpairin g the resulting product. Again, the interstices of the hay-rope windings are not uniform andot'ten allow the clay layer to seat against the corebar, and thus the hardening of the earthy layers and the shrinkage of the casting render the withdrawal of the core-bar diihcult or impossible without breakage or serious in: jury to the casting.

The object of my invention is to provide a novel method of manufacturing a core which avoids the expense of hay rope, also the clay layer applied tothe rope,and that shallbe free from the objectionable features named and more rigid and elicient, thereby not only economizing in cost, but producing castings quality and avoiding the loss d ue to imperfect COI'OS.

To this end my'inventionconsists in the method of making a core built upon a core# bar in which the. hay rope is' replaced by a foundation layer of earthy matter having a suiicient proportion ot combustible material disseminated through the same to render it extremely porous and friable when subjected to the heat of the casting, so that the core may be readily withd rawn. requires but a thin outer surfacing-coat of loam, which is therefore easily broken from the casting.

In the drawings attached hereto, illustrating the structural features of a core applied to the casting of water or gas pipe, Figure l exhibits apartial axial section of a i'lask prepared for the reception of molten metal with the core in place, Fig. 2, a horizontal crossseetion of the sameparts in the plane of Fig. l.

In the drawings, F designates a flask prepared for the casting of a pipe in the space s, and A the core-bar suited to the inner contour of the pipe to be cast.

For the purpose of my invention the corebar A is a cylindrical casting ot' metal, usually hollow, having a large number of ventopenings o through the shell. Immediately upon the perforated surface of the core-barl place a layer B of material formed and applied as follows: The material of this layeris preferably about one-third part pulverized earthy material (such as the spent core-dirt of the pipe works) and two-thirds comminuted woody combustible material, thoroughly mixed and worked into a plastic mass, somewhat adhesive, with water and applied as a concentric layer directly upon the surface of the core-bar. The earthy material may containa sufficiency of loam or of mineral cement to render the ultimate mass somewhat adhesive to and reasonably firm, when dried, upon the core-bar. The combustible material may be sawdust, ground leaves, straw, seaweed, &c., or any cheap material of this nature capable of being disseminated in a finely-divided state throughout the mass, or spent core-dirt may be used in connection with mucilagnous matter otherwise introduced-as, for example, a

The core so made IOO ing the o uter layer of clay over the hay rope r' or may be applied by means of a flexible web, such as is sometimes employed in the manufacturel of earthen pipe, and when applied/ the layer is dressed to a 4uniform thickness and comparatively Smooth surface. It is then thoroughly dried to expel moisture. InI f aslnuch` as the layer contains so large a proi -layer B may also vary largely, according to portion of woody fiber, Whichis very absorbent, the mass as made contains an excess of moisture, the drying out of which rendersit rin and exceedingly porous. After the preparation ofthe inner layer as described a-thin manner and dressed to a true cylindricalsurface throughout. toa second dryingand is finished-in the usual manner. Tlreis thus -prodvucedacore consisting of the, core-bar A, a layer of partially--A combustible material B surro undihg thesame,v andthe outer. layer b of loam forming the iinished and smooth exterior. 'VI-The large proportion and uniform distribution of the Woody constituents ofthe initial layer renders it exceedingly porous in its dry state, and this constituent being combustible is Pconsumed by theintenseheatof. the adjacent molten metalI casting operation is sufficiently slow to en,- able the outer layer b to retain its proper form` Qfgthe casting, thus rendering the inner layer` jtowork well in practice. inishing-coatb `oi loam is applied in the usual by Letters Patent of the UnitedStates- The core is then subjected "for casting hollow cylinders, pipe, &c;,con-

until themetal sets, Wlile at the same time the inner layer vis surciently porous,n corinection with the apertures o, to aerd the proper ventkfor the gases engendered'in casting and also; to freely admit air to eect combustion of the combustible material of the 'innerlayer B. f' Y As a result of the proper application of the invention the construction of cores is con- .siderablyeconomized and more accurate and uniform castings are produced,besides largely decreasing the percentage of failures or imperfect, castings.

rlhe composition, both as to character and :proportion of the constituents, of the initial local conditions and conveniences. Thegeneral aimis to em ploy the most inexpensivev marterials,1and those designated have been/found I'claim as my invention and desire to secu re The improvement in the art of forming cores .'sisting in iirst` coating I the perforated core- :bar With a plastic adhesive mass of moist *earthy material containing a large percentage of combustible material in comminuted state; thenl dryingthe same tosct andV render it fporgus; and lastly covering the saidcoa ting iWith a finishing-coat of loam, and-.drying the @same in the usual manner, substantially as set forth. y

In testimony whereof., l have hereunto set my hand in the presence o f two subscribing iwitnesses.-

i Y MORDEOAII-L FLETCHER.

Witnesses:

a L. M. Hosen,

f FRANK K. BOWMAN. 

